On Mon, 2011-10-31 at 14:35 +0100, Bernd Zeimetz wrote: > Package: linux-2.6 > Version: 2.6.32-38 > > Hi, > > removing paths to our SAN and adding them back results in [...] Does the attached patch help? Instructions for building a patched kernel can be found at: http://kernel-handbook.alioth.debian.org/ch-common-tasks.html#s-common-official Ben. -- Ben Hutchings Sturgeon's Law: Ninety percent of everything is crap.
From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Date: Thu, 12 Aug 2010 04:13:54 +0100
Subject: [PATCH] dm: prevent access to md being deleted
commit abdc568b0540bec6d3e0afebac496adef1189b77 upstream.
This patch prevents access to mapped_device which is being deleted.
Currently, even after a mapped_device has been removed from the hash,
it could be accessed through idr_find() using minor number.
That could cause a race and NULL pointer reference below:
CPU0 CPU1
------------------------------------------------------------------
dev_remove(param)
down_write(_hash_lock)
dm_lock_for_deletion(md)
spin_lock(_minor_lock)
set_bit(DMF_DELETING)
spin_unlock(_minor_lock)
__hash_remove(hc)
up_write(_hash_lock)
dev_status(param)
md = find_device(param)
down_read(_hash_lock)
__find_device_hash_cell(param)
dm_get_md(param->dev)
md = dm_find_md(dev)
spin_lock(_minor_lock)
md = idr_find(MINOR(dev))
spin_unlock(_minor_lock)
dm_put(md)
free_dev(md)
dm_get(md)
up_read(_hash_lock)
__dev_status(md, param)
dm_put(md)
This patch fixes such problems.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: stable@kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
drivers/md/dm.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a3f21dc..ba6934c 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2136,6 +2136,7 @@ static struct mapped_device *dm_find_md(dev_t dev)
md = idr_find(&_minor_idr, minor);
if (md && (md == MINOR_ALLOCED ||
(MINOR(disk_devt(dm_disk(md))) != minor) ||
+ dm_deleting_md(md) ||
test_bit(DMF_FREEING, &md->flags))) {
md = NULL;
goto out;
--
1.7.7
Attachment:
signature.asc
Description: This is a digitally signed message part